Wikibooks: Structural Biochemistry/Final Review/Midterm III

• Format: Book
• Language: English
• Subjects: Carbonic acid
• Online Access: https://en.wikibooks.org/wiki/Structural_Biochemistry/Final_Review/Midterm_III

= How does carbon dioxide affect hemoglobin? = Carbon dioxide decreases the affinity of hemoglobin for oxygen. This is because CO 2 reacts with water with the help of carbonic anhydrase to form carbonic acid. this lowers the pH which in turn lowers the affinity of oxygen to hemoglobin. = What are the differences between myoglobin and hemoglobin? = Hemoglobin tetramer with beta and alpha subunits with a Fe metal center at the active site more efficient O 2 carrier from lungs to rest of the body due to easy release of ligand (O 2 ) weaker hold on and lower affinity for O 2 cooperative molecule with two distinct states T (tense) and R (relaxed) as pH decreases the O 2 affinity decreases and vice versa better release of ligand when low pH inside red blood cells Myoglobin single polypeptide with Fe metal center at active site controls reactivity of Heme group to prevent release of reactive O 2 stronger hold on and higher affinity for O 2 better carrier choice in muscle cells Fe gets oxidized from II to III through binding of O 2 works better if remains in dioxygen form and not superoxide = Describe the catalytic mechanism of chymotrypsin? = 1. Binding of substrate 2. A nucleophilic attack of serine on the peptide carbonyl group 3. Collapse of the tetrahedral intermediate 4. The release of the amine component 5. Water binds (hydrolysis) 6. Nucleophilic attack of water on the acyl enzyme intermediate 7. Collapse of the tetrahedral intermediate 8. Release of the carboxylic acid component = What is a zymogen why are they created by the body? = A zymogen is an inactive precursor of an enzyme. The reason for cells to secrete inactive enzymes is to prevent unwanted destruction of cellular proteins. = What are the two models for the formation of Golgi complex? = 1. CISTERNAE MATURATION describes that golgi was made from scratch and that proteins from the ER fused and matured to create the specific compartments. 2. VESICULAR SHUTTLE MODEL describes that golgi was a pre existing structure within the cell and that its function ...